Please help! My five year old daughter acts like a moody teenager

She's defiant and moody, slams doors and has an answer to EVERYTHING! I thought i had a few years to go before she'd start to give us this sort of attitude. She's the same with her dad and even with her grandparents! We send her to her room when she's being like this and ban TV and other treats but nothing seems to bother her. Does any one else have this problem? any solutions? thanks